The objectives of the proposed research project are: 1) to establish and maintain a breeding colony of Hageman trait cats, 2) to define the nature of Hageman trait in the cat in relation to: a) its genetic mode of transmission; b) its hematologic character, i.e., whether the deficiency is in fact due to lack of Hageman factor activity or due to a plasma inhibitor; c) its antigenic character, i.e., whether the deficiency in Hageman factor activity is due to lack of the protein molecule or due to a defective molecule, 3) to use Hageman trait cats as an animal model to study endotoxin induced DIC. Thus defining the Hageman factor deficiency in the cat will establish its advantage for future use for in vivo investigations of the role played by factor XII in the activation of complement, fibrinolysis, inflammation, and coagulation.